Furthermore, the invention relates to a process for the preparation of polyunsaturated fatty acids and to a process for introducing DNA into organisms which produce large amounts of oils and, in particular, oils with a high content of unsaturated fatty acids. Moreover, the invention relates to an oil and/or a fatty acid preparation with a higher content of polyunsaturated fatty acids with at least two double bonds and/or a triacylglycerol preparation with a higher content of polyunsaturated fatty acids with at least two double bonds.
Certain products and byproducts of naturally occurring metabolic processes in microbial cells or in the cells of animals and, advantageously, plants can be used for a wide spectrum of industries, including the animal feed industry, food industry, cosmetics industry and pharmaceuticals industry. These molecules, which are joinly referred to as “fine chemicals”, also include lipids and fatty acids, amongst which the polyunsaturated fatty acids constitute an example of one class. Polyunsaturated fatty acids (PUFAs) are added, for example, to food for children to increase the nutritional value of these foods. For example, PUFAs have a positive effect on the cholesterol level in the blood of humans and are therefore suitable for protection against heart disease. Fine chemicals such as polyunsaturated fatty acids (PUFAs) can be isolated from animal sources, for example fish or produced on a large scale using microorganisms by growing microorganisms which have been developed in such a way that they produce and accumulate or secrete, large amounts of one or more desired molecules.
Microorganisms which are especially suitable for preparing PUFAs are microorganisms such as algae such as Phaeodactylum tricornutum or Crypthecodinium species, Ciliata such as Stylonychia or Colpidium, fungi such as Mortierella, Entomophthora or Mucor. A number of mutant strains of the microorganisms in question which produce a series of desirable compounds, including PUFAs, have been developed by strain selection. The selection of strains with an improved production of a certain molecule is, however, a time-consuming and difficult procedure.
As an alternative, fine chemicals can suitably be produced on a large scale via the production of plants which have been developed in such a way that they produce the abovementioned PUFAs. Plants which are particularly well suited to this purpose are oil crops which contain large amounts of lipid compounds, such as oilseed rape, canola, linseed, soya, sunflowers, thistles, borage and evening primrose. However, other crops which contain oils or lipids and fatty acids are well suited, as mentioned in the detailed description of the present invention. Conventional plant breeding via the selection of suitable plants has led to the development of a series of mutant plants which produce a spectrum of desirable lipids and fatty acids, cofactors and enzymes. However, the selection of novel plant varieties with an improved production of a certain molecule is a time-consuming and difficult procedure or even impossible if the compound does not occur naturally in the plant in question, such as in the case of polyunsaturated C20-fatty acids and those with longer carbon chains.